Project Summary/Abstract Parent emotion-related talk (e.g., use of emotion language) with children has been shown to be associated with later externalizing behavior problems. However, most studies examining parent emotion-related talk have relied on cross-sectional designs and therefore have been unable to understand how parent emotion-related talk changes over time. Existing studies also have primarily included preschoolers and older children, and only a few studies have examined the relation between parent emotion-related talk, child prosocial behavior and emotion regulation with infants and toddlers. Deficits in prosocial behavior and emotion regulation are associated with poor long term outcomes, including impairment in academic functioning and peer relationships, which may be increased by behavior problems. Early signs of behavior problems place these families at high risk of developing later externalizing problems. Considering the high risk of later externalizing problems, it is important to understand if there are differences in parent emotion-related talk in infants and toddlers from low- and high-risk families. The developmental trajectory of parent emotion-related talk (Research Aim 1) and the impact of parent emotion-related talk on infant prosocial behavior and emotion regulation will be examined (Research Aim 2). Specifically, growth curve modeling will be used to examine changes in parent emotion- related talk over time and structural equation modeling using multiple units of analysis, including observational assessment of behavior and parent report will be used to examine the effect of parent emotion-related talk on infant emotion regulation and prosocial behavior. In addition, differences in parent emotion related talk between parents of infants at low and high risk of behavior problems will be examined (Research Aim 3). Mentoring with Dr. Bahrick and Dr. Reeb-Sutherland will consult on normative infant development (Training Goal #1). Dr. Denham will consult on measurement of emotion understanding and socialization, and Dr. Graziano will consult on assessment of emotion regulation (Training Goal #2). Dr. Coxe will consult on developing advanced quantitative skills longitudinal data analyses (Training Goal #3). Dr. Bagner will consult on the impact of parenting practices on infant development and the unique needs of high-risk families, as well as supervise and consult on the overall proposed study and ethics. Findings will inform future work to examine possible mechanisms by which parent emotion-related talk can be targeted to help improve child social, emotional, and behavioral outcomes. The proposed training goals and research aims will prepare me for a career as an independent investigator focused on impact of parent-child interactions on the development of emotion in early childhood.